FGF23 related rickets/osteomalacia was mainly composed of XLH, ADHR, ARHR1, ARHR2 and tumor induced rickets/osteomalacia. Although the mechanism for increasing serum FGF23 levels was different from disease to disease, therapies for these patients were basically the same ; pharmacological doses of active vitamin D and phosphate administration. It is noted that phosphate therapy is associated with the occurrence of secondary hyperparathyroidism and nephrocalcinosis. Moreover, recent evidences indicated that these combination therapies increased serum FGF23 levels. On the basis of these data, it is suggested that appropriate doses of active vitamin D and phosphate are to be selected according to the data of serum PTH, ALP and the amount of urinary excretion of calcium. For the children, the recovery of growth velocity is also an important factor for deciding the suitable doses of the therapies.